In order to achieve a high level of durable press characteristics for some cotton fabrics, it has been necessary to treat such fabrics with a resin, such as formaldehyde, in the order of 5%-10% by weight. Such treatments invariably weaken the tensile strength of the fabric, particularly in the filling direction. In recent years, commercialization of a process for the liquid ammonia treatment of cotton fabrics has become an accomplished fact. In such treatment, the "hand" and wrinkle resistance of cotton fabrics is improved, imparting at least in the heavier fabrics a durable press effect. Such treatment also improves the tensile strength of the fabric and is commonly used in conjunction with a subsequent resin treatment of medium and lightweight fabrics in order to achieve a high level of durable press characteristics, while negating to a large extent the weakening effect of the resin treatment upon the fabric.
A special problem is presented when a pile fabric such as corduroy or velvet is treated according to known methods for durable press purposes. When an untensioned fabric is immersed in liquid ammonia, shrinkage occurs which can exceed the washing shrinkage by two or three times. This excessive shrinkage is normally controlled by applying tension to the fabric or by combined time and tension control. When pile fabrics such as corduroy or velvet are treated with liquid ammonia, the pile on such fabrics shrinks excessively since it is attached at one end only and hence is tensionless (the pile being freestanding and attached to the base fabric).
Additionally, during the drying of an ammonia saturated fabric at a specified level of residual ammonia, the fabric becomes easily distorted. Since many existing commercial ammonia finishing ranges utilize blanketed cylinders for fabric drying, the normal pressure of the blanket against the fabric distorts and flattens the pile. It is the purpose of the present invention to disclose a method of treatment combining resin treatment and liquid ammonia treatment of pile fabrics in such a manner as to minimize the problems of pile shrinkage, flattening and distortion which greatly improves the appearance of such pile fabrics.